When new node image is being created, vdsm.rpm is added to the node image and self-signed key (and certificate) is created. This key/cert allows vdsm to start and serve requests from anyone who has a matching key/cert which could be anybody holding the node image.
Upstream fix:
http://gerrit.ovirt.org/#/c/8368/
Acknowledgements:
This issue was discovered by Dan Kenigsberg of Red Hat.

Statement:
Not vulnerable.
This issue did not affect the versions of vdsm22 package as shipped with Red Hat Enterprise Linux 5. This issue did not affect the versions of vdsm package as shipped with Red Hat Enterprise Linux 6. This issue did not affect the hypervisor disk images as shipped with Red Hat Enterprise Virtualization Hypervisor 5 and 6.